Anthony Flack wrote:Not to say these aren't comparatively rare events - I think a sphere of one tenth of a cubic GPc should contain nearly a million galaxies...? So we're talking about something that happens maybe once per year across 30,000 galaxies.

Honestly, that's a lot less rare than I thought. I remember reading a book about black holes saying we had never witnessed a merge, but now that I think about it, I think I read that book a decade ago.

I'm glad we have some real numbers about it. Amazingly cool that we were able to pull this off nonetheless. One of the interesting things I read was that indirect proof of gravity waves was found by observing dual rotating neutron stars. That won a nobel. Maybe this will too.

Reports on this mention that this is indeed the first time we've witnessed a merge, but it must be awfully difficult to detect one with a conventional telescope from a billion light years away - assuming you even knew which one of a million galaxies to look at.

Essentially every other prediction of GR has been found to be correct, but the existence of gravitational waves has been maddeningly difficult to prove directly.

Until now. And what caused the gravitational waves they detected at the Laser Interferometer Gravitational-Wave Observatory is as amazing and mind-blowing as the waves themselves: They caught the death spiral and aftermath of two huge black holes 1.3 billion light-years from Earth, merging together in a titanic and catastrophically violent event.

Mind you, we’ve had some good evidence such binary black holes existed before this, but this new result pretty much proves they exist and that, over time, they eventually collide and merge. That’s huge.

The black holes had masses of 36 and 29 times the mass of the Sun before they merged. After they merged they created a single black hole with a mass of 62 times that of the Sun. You may notice those masses don’t add up right; there’s 3 solar masses missing. That mass didn’t just disappear! It was converted into energy: the energy of the gravitational waves themselves. And the amount of energy is staggering: This single event released as much energy as the Sun does in 15 trillion years.

If one of these goes off in any given galaxy once every 30,000 years, maybe not so bad as that. But that may be making too many assumptions about the kinds of galaxies this happens in (or happened in). Maybe it's much less likely to occur in a galaxy like ours. But it seems likely that the Earth has been whacked with at least a few of these from inside the Milky Way at some point during the history of life.

The energy arriving at any point is going to be proportional to the inverse square of the distance, just like a sound wave or any other expanding spherical wave. So it should dissipate fairly quickly. If you were 100,000 light years away which is the diameter of our galaxy, and 10,000 times closer to the event than us, it would be 100 million times stronger, but considering how minute the effect was out here, I'm not sure if that would be particularly bad.

I guess it shouldn't be too hard to calculate how three solar masses of energy would dissipate at various distances.

Bigelow just got a contract for one of their large inflatable modules to be added to the ISS for testing this is one of the full size ones B330 (they had a smaller test one sent up last year) and they will test it once installed for radiation and such. Hopfully if this proves out NASA will be able to cheaply add a bunch of modules to increase the size of the station dramatically and prepare them for a bunch of their other future planned projects.

When they were planning the ISS the inflatable modules were considered but they went with tried and true tech (heavy weight metal) because of having the Shuttle to send the parts up. Though everyone involved felt this tech would in time be used for future stations and bases. The designer went independent from NASA with Bigelow and now this tech gets its development shot. As well Bigelow was laying off people last month so this is a much needed shot in the arm financially and in terms of credibility. Astronauts visiting the display of the 330 were impressed by its open space.